In Ghana, information on plants antagonistic to nematodes is scanty compelling farmers to rely on synthetic chemicals which are effective but pose an environmental threat. This work aimed to evaluate the effect of aqueous leaf extracts of Khaya senegalensis, Tectona grandis, Azadirachta indica, Vernonia amygdalina and Bryophyllum pinnatum plants for the control of Meloidogyne spp. In evaluating the botanicals, a laboratory, field and pot experiments were conducted. The first experiment evaluated the effect of extracts from fresh leaves of K. senegalensis, T. grandis, A. indica, V. amygdalina and B. pinnatum on eggs hatchability and nematicidal activity against second stage juveniles of Meloidogyne spp in the laboratory. Results show that lower egg hatch and higher juvenile mortality occurred in the extracts and was concentration dependent. A. indica at 25% gave the lowest mean egg hatch of 2.33 and highest juvenile mortality of 65.16. The second experiment was carried out to evaluate the effect of aqueous leaf extracts of K. senegalensis, T. grandis, A. indica, V. amygdalina and B. pinnatum applied to soil as drench on tomato plants. Although the botanicals were effective in the laboratory and pot experiments, they were moderately effective in the field.. The third experiment was carried out to evaluate the application of leaf extracts of K. senegalensis, T. grandis, A. indica, V. amygdalina and B. pinnatum as mulch and soil admixture on growth and severity of nematode infection on tomato plants. The results indicated that K. senegalensis, T. grandis, A. indica, V. amygdalina and B. pinnatum applied as soil-admixtures were more effective in controlling Meloidogyne than applied as mulch.

Tomato (Solanum lycopersicum L.) is one of the most widely accepted fruits in the world because it is mostly consumed worldwide. It is one of the most important nutritious vegetable crops grown around the world. Ali et al., (2012) have reported that, in terms of area cultivated, tomato ranks next to potato whereas, as a processing crop it ranks first in the world. It belongs to the family of Solanaceae, including crops such as eggplant, pepper, tobacco and potato.

Tomato is believed to have originated from tropical central and South America (Cobley & Steele, 1974). Its cultivars in Africa are believed to have descended from varieties later introduced from Europe (Villareal, 1980). Several researchers have shown that it was introduced in Ghana in the 16th and 17th centuries by the Portuguese and has become the most popular vegetable crop (Norman 1992 & Nkansah et al., 2003). Amuti, (1971) stated that most of the local varieties produced in Ghana today evolved from varieties that were introduced by the Portuguese in the 16th and 17th centuries.

Several researchers have reported that not all varieties are successful for cultivation in the country. This observation was made by some researchers who noted that in the coastal savannah areas of Ghana, varieties which proved successful for cultivation are the local types, Fireball, Wosowoso, OK1, OK5, OK7-2, OK7-3, ImprovedZuraungu, Marglobe, Victor and Pusa Early Dwarf (Sinnadurai, 1967; Amuti, 1971 & Blay, 1978).

Tomato has a good adaptation to a wide range of climatic conditions, and so is found throughout tropical Africa (De Lannoy, 2001). According to FAO (2005), Ghana has wide range of areas that are suitable for tomato production. Production of the crop in Ghana is done by small-scale farmers who grow it basically for its fresh use. However, with the introduction of irrigation projects, large scale monoculture has become wide spread, especially in the Northern and Upper Regions, and around southern Volta region. Tomato production is also vibrant in Akumadan and the Wenchi Districts. Tomato is also grown commercially at Derma, Techimantia and Tanoso in the Brong-Ahafo region. Cooperative farming according to Norman (1992) is concentrated around Mankessim, Swedru, Nsawam, Amasaman, Sege and Dodowa. Farming methods applied for tomato cultivation are often based on availability of water. The sources of water such as rainfall, irrigation, wells and riverbeds determine both the season of farming and the number of times farming is undertaken within the year. In addition, post harvest losses are very high in Ghana especially during the peak harvesting period when there is a glut. Norman (1992) reported that production and yield of tomato in Ghana is affected by several factors. Pests and diseases have been found to be a major constraint to production, and these affect the quality and quantity of the produce. Major pests that attack tomato include plant parasitic nematodes (Berlinger, 1986).

Tomato is an important crop in Ghana (Norman, 1992). It can be grown under varied conditions; from green house to the field. It contains important chemical compounds of medicinal importance (Sahlin, 2004). The ripe tomato fruit is rich in vitamins and a good sourec of A, B, C and minerals which areimportant in the human diet (Willcox Catignani & Lazarus, 2003). About 125 million tonnes of fresh tomatoes were produced in the world in 2008 (FAO, 2010).

In Ghana, about 12,000 hectares of land are under tomato cultivation and it is estimated that more than 60,000 farmers grow tomato; Policy Planning and Monitoring and Evaluation Departmentof the Ministry of Food and Agriculture(PPMED, 1993). In 1987, tomato contributed about 130,000 metric tons to the total agricultural productions and about 13 billion cedis in revenue to the Ghanaian economy (PPMED, 1991). Tomato is one of the major sources of income to farmers and traders in Ghana. It’s usefulness in fresh or processed form has played a major role in its rapid and widespread adoption as an important food commodity in the country (Norman, 1992, Horna, Melinda

Jose., 2006 and Asare-Bediako, Showeminio and Buah& Ushawu., 2007). The crop is the largest contributor to Gross Domestic Product (GDP) in the countryGhana Statistical Service (1999). In 2004, tomato alone contributed 607 metric tons to the total agricultural growth and about US$ 56,000 in revenue (SRID, 2005).

F A O in 2005 reported that tomato contributed $437,000 to the Ghanaian economy from export of 4,368 metric tonnes.

Despite the intensive cultivation and potential of tomato in the tropics, yield in Ghana is very low compared to other tropical countries. GIPC (2005) and Danquah and Fulton (2007) reported that yield of tomato in the country is still low (about 7.5 tonnes/hactare) compare to other tropical counties like Nigeria at 1,860,600metric tones (FAO, 2010). The global production area for tomato in 2010 was estimated at 151,699,505 tonnes (FAO, 2010). Production in the United States of America in 2010 was 12,858,700 tonnes (FAO, 2010), Ghana produced just three tonnes per hactare (SRID, 2010). The low production of tomato in the tropic and sub-tropical regions has been attributed to the persistent pest problems and inadequate pest management practices (COPR, 1983). Some of these problems include limited availability of improved planting material, high cost of labour for land preparation, staking, weeding, harvesting, storability, and nematode diseases among others. Root-knot nematodes (Meloidogyne spp) according to De Lannoy (2001) are the major pest of tomato.

Meloidogyne arenaria, Meloidogyne javanica and Meloidogyne incognita are reported as the main species which attack tomato Clerk (1974). Apart from tomato which is highly susceptible other members of the Solanaceae family like the garden egg, pepper and tobacco when grown on even lightly infested land, fail to produce any remarkable fruit and on severely affected soil they are killed totally while still young Clerk (1974).

Hemeng (1981) observed 73 – 100% yield loss in tomato in the Guinea Savannah Zone of Northern region of Ghana to be caused by root-knot nematodes.

Even though Farmers use a high percentage of their income to fight nematodes problems every year, their effort is still not enough to reduce the losses. Mostfarmers would not use nematicide; rather nematicides are recommended like carbofuran as control measure against root knot disease, but expensive and these chemicals are toxic to animals and man and therefore pose great danger to peasant farmers most of whom are illiterates (MoFA, 1995).

Current efforts and campaign being made by Governments of various countries including Ghana to improve the standard of living through the production and utilization of vegetable (like tomato), could only be successful if solutions to the problems of pests including plant parasitic nematodes are found. MoFA (1995) reported that the use of synthetic nematicides is considered the most effective practical means of combating the menace of plant parasitic nematodes in tomato but has some serious constraints. The assault on the environment through the indiserminate use of synthetic agro-chemicals (Bell, 2000) and unreliable results from crop rotation systems (Sikora & Fernandez, 2005) has necessitated the search for sustainable, effective and environmentally acceptable nematode management options.

The World Health Organization (WHO) reported that 20% of pesticide use in the world poses danger to human health as well as the environment (Hurtig et al., 2003). Higher level of pesticide has been found in people residing closer to agricultural fields (Quandt etal., 2004). It has also been reported that in late 2010, 15 farmers died from suspected pesticide poisoning in Upper East region of Ghana (NPAS, 2012).

Currently the Ghanaian public and government have come to realize that the use of chemical pesticides by vegetable farmers to control pests and diseases in the country is increasing and if agricultural production is to be sustainable and safe to humans and the environment, then intensive farming systems should become less dependent on chemical pesticides (Okorley, Zinnah & Bampoe., 2002).

With concern about the adverse long-term effects of pesticides on the environment and human health adequate measures are therefore required to promote the appropriate management of pests and pesticides. Proper management will ensure that increased and sustainable agricultural production and farm incomes are achieved; that diseases and insect pest are managed in a sustainable manner, and that the risks to human health and the environment associated with pesticide use are kept to an acceptable level.

The use of plant extracts and antagonistic microorganisms as a component of integrated nematode management is gaining wide acceptance worldwide. Their environmental safety in an environmentally conscious world also holds promise for their acceptability and use by resource-poor African farmers Egunjobi and Onayemi, 1981 Zurren and Khan, 1984; and Adegbite, 2003.

The potential for nematicidal activity of indigenous plants and their products as an alternative for traditional nematicides has been studied by several works Prot and Kornprobst, (1983); Haseeb, Siiddiqui and Alam, (1984), Pracer, Tarjan and Hodgson,(1987); Osmam and Viglierchio, (1988); Adegbite and Adesiyan (2005); and Hasabo and Noweer (2005).

The use of botanical extracts for controlling pest is appealing because of the growing problem of environmental pollution caused by synthetic nematicides. Plant extracts have been found to be effective for the control of plant parasitic nematodes Siddiqui and Allam (1987), (Hussain, Kumar, Kahn & Tito, 1984); they are easily degraded, leave no harmful residues, are cheaper, nontoxic to host plant and humansand availability in many tropical countriesAmadioha, (2003). Extracts of many plants with anti-helminthic and antimicrobial properties have been proven effective in controlling plant parasitic nematodes (Ferris & Zheng, 1998). Such plant species produce different allele-chemicals which have tremendous nematicidal potential (Sukul, 1992). Compounds occurring in the plants with nematicidal activity comprise a wide variety of phytochemicals e.g. polythienyls, acetylenes, alkaloids, fatty acids and derivatives, phenolics, terpenoids alkaloids, fatty acids and derivatives, phenolics, terpenoids (Chitwood, 1992).He further stated that use of phytochemicals in crop production could offer sustainable management option.

Nematicidal phytochemicals are generally safe for the environment and these compounds include repellents, attractants, hatching stimulants or inhibitors and nematotoxicants, either constitutive or formed in response to nematode presence (Chitwood, 2002). Information on plants antagonistic to nematodes is scanty compelling farmers to rely on synthetic chemicals which are effective but pose an environmental threat (Osei, Fening, Gowen & Jama, 2010) this lead to increased interest in developing pesticides of natural origins during recent years.

The objective of this study was, therefore to evaluate the use of aqueous leaf extract of some plants in Ghana for the management of root-knot nematode infection on tomato.

The specific objectives were to evaluate:
The effect ofAzadirachta indica, Bryophyllum pinnatum, Khaya senegalensis, Tectona grandis and Vernonia amygdalina on egg hatchability and nematicidal activity against juveniles of Meloidogyne spp.

The effect of the aqueous leaf extract of the five medicinal plants on growth and yield of tomato in the field.

The application of the five plants Azadirachta indica, Bryophyllum pinnatum, Khaya senegalensis, Tectona grandis and Vernonia amygdalina extracts as mulch and soil admixture for the control of root-knot disease and growth of tomato.

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